1. Field of the Invention
The present invention is generally related to a data recording method for a marine propulsion device and, more specifically, to a method for recording data using alternating groups of data logs in which each of the data logs in a group contains data stored at different incremental times.
2. Description of the Prior Art
Many different systems are known to those skilled in the art for storing data relating to a vehicle, such as an automobile or airplane. U.S. Pat. No. 4,729,102 which issued to Miller et al on Mar. 1, 1988, describes an aircraft data acquisition and recording system. The system combines flight data recorder data acquisition circuitry and airborne integrated data circuitry that can be variously packaged to supplement and update existing aircraft systems or serve as a standalone flight data recording and/or airborne integrated data system. The flight data recorder system circuitry and airborne integrated data system circuitry are separately programmed microprocessor based systems that are capable of processing aircraft parametric signals provided by a variety of aircraft signal sources. The airborne integrated data system circuitry is arranged and programmed to automatically monitor engine start and shutdown procedures, airplane takeoff and cruise and to provide a landing report that indicates fuel consumption and landing weight. To minimize memory storage requirements and provide readily available engine condition information, the automatic monitoring consists of a single set of signals for each monitored condition and the information is converted to standard engineering units. Monitoring of selected parametric signals to detect excessive levels also is provided. Stored data is periodically retrieved by means of a ground readout unit.
U.S. Pat. No. 5,033,010, which issued to Lawrence et al on Jul. 16, 1991, discloses a turbine engine monitoring system which disposes a data storage device in permanent association with an engine being monitored. The data storage device comprises an electrically erasable programmable read-only memory which is contained in an enclosure and permanently attached to the engine. A connection link is provided to connect the memory device in signal communication with an external device, such as an engine control unit. The engine control unit is connected in signal communication with a plurality of transducers that enable the engine control unit to monitor the operational status of a plurality of parameters relating to the turbine engine. By permanently attaching the data storage device to the turbine engine, a lifetime information of the turbine engine can be maintained in permanent association with the turbine engine regardless of replacement of the turbine engine or its related engine control unit.
U.S. Pat. No. 4,575,803, which issued to Moore on Mar. 11, 1986, describes an engine monitor and recorder. The system includes an engine mounted unit which contains at least a non-volatile memory and a data processor and a remote unit suitable for either cockpit mounting or for accessing by a ground portable unit including an additional data processor and a display unit. Thermocouples and other sensors mounted on the engine supply raw data to the engine mounted electronics unit, and this input information includes temperature data. Elevated over-temperature levels are segregated and the time during which the engine is within each of the over-temperature bands is measured, and is recorded in an non-volatile, electronically alterable memory which is periodically updated during operation of the aircraft. The number of starts is also counted and stored, and the total running time of the engine is also recorded. Upon command from the remote unit, information is transferred from the non-volatile memory to the remote display unit, so that the time at which the turbine has been operated at specific over-temperature levels may be readily accessed.
U.S. Pat. No. 3,946,364, which issued to Codomo et al on Mar. 23, 1976, describes a method and apparatus for sensing, storing, and graphically displaying over-temperature conditions of jet engines. The required frequency of inspection, servicing and overhauling of jet engines is to a large extend determined by the history of excessive or over-temperature conditions of each engine. In order to monitor and record each such over-temperature condition, an indicator device is provided having electronic circuitry for processing a temperature signal from the jet engine and a light emitting diode matrix for graphically displaying each over-temperature incident. When the jet engine temperature exceeds a threshold over-temperature point, this occurrence is sensed and the circuitry of the indicator functions to automatically store and visually display the engine temperature as a function of time for the succeeding several seconds after the over-temperature condition has commenced. All the diodes of the matrix lying under the temperature versus time profile are energized so as to present a histogram display of the severity of the condition, where the severity is a function of the duration and magnitude of the over-temperature. In one embodiment disclosed in the patent, a plurality of over-temperature events are automatically sensed, graphically displayed and stored for later retrieval, such that the maintenance crew may subsequently interrogate the indicator device causing it to sequentially display each recorded or electronically stored over-temperature event.
U.S. Pat. No. 5,581,464, which issued to Woll et al on Dec. 3, 1996, describes the recording of operational events in an automotive vehicle. The device provides an event recording apparatus (ERA) that records selectable vehicle performance, operational status, and/or environment information, including information useful for accident analysis and updated software for use by a system processor capable of reading data from the ERA. The preferred embodiment of the ERA comprises a non-volatile solid-state memory card, a memory card adapter located in a vehicle, and a micro-processor, either as part of the memory card or embedded in a system within the vehicle, for controlling the storage of data within the memory card. The ERA is configured to store such information as the closing rate between the recording vehicle and targets located by the vehicle""s radar system, distance between the recording vehicle and targets, vehicle speed, and such vehicle operational status and environmental information as braking pressure, vehicle acceleration or deceleration, rate of turning, steering angle, hazard levels determined from a radar system processor, target direction, cruise control status, vehicle engine RPM, brake temperature, brake line hydraulic pressure, windshield wiper status, fog light status, defroster status, and geographic positioning information. In addition, the ERA can be configured to function as a common trip monitor, recording distance traveled, average speed, miles-per-gallon, fuel remaining, compass direction of travel, etc. The device can also record vehicle maintenance information, such as oil temperature, engine temperature, transmission fluid temperature, and engine timing.
Although the prior art teaches many different types of data recording mechanisms and methods for use in conjunction with a vehicle, such as an automobile or airplane, known methods of data storage do not directly address two problems associated with the recording of operational data for a vehicle. First, known recording systems either begin the process of recording data upon the occurrence of an event, such as a vehicle accident evidenced by an activation of an airbag system, or the occurrence of a deleterious operational parameter, such as an over-temperature condition within a cooling system of an engine. Secondly, known systems of this type often utilize mass data storage devices with a high storage capacity in order to store many thousands of data points. Thirdly, data storage systems known to those skilled in the art often do not provide a capability for protecting previously stored data permanently even though the vehicle is restarted and operated subsequent to the event intended to be monitored.
It would therefore be significantly beneficial if a data recording system could be provided in which data is continuously monitored at two or more data acquisition rates in order to provide relatively long term analysis in combination with a much more detailed analysis of the time period immediately preceding a catastrophic event, such as an accident or machine failure. In order to minimize the required memory to accomplish these purposes, it would be significantly beneficial if a system could monitor both short term and longer term usage of a vehicle and, in addition, allow the vehicle to be operated after a catastrophic event without destroying the stored data prior to the event.
A data recording method, in accordance with the preferred embodiment of the present invention, comprises the steps of providing first and second groups of data logs. The data logs can be three in number in each group and each data log can comprise twenty data records. Information is stored at different rates in each of the data logs. The present invention further comprises the step of monitoring an operating status of the marine propulsion device, such as an outboard motor, inboard engine, or stern drive unit. Throughout the description of the present invention, xe2x80x9coutboard motorxe2x80x9d shall be used to mean any marine propulsion device which comprises an engine and is attachable to a transom of a marine vessel. The operating status can be represented by the on/off status as represented by an ignition switch or ignition key. The recording method of the present invention further comprises a step of measuring a magnitude of a first parameter. The first parameter can be selected from a group consisting of engine speed (RPM), engine running time, boat speed, steering angle, trim position, throttle position, or gear selection. In addition, embodiments of the present invention can measure the magnitude of a plurality of parameters, in which each of the plurality of parameters is treated in a manner similar to the method described below. The method of the present invention further comprises the step of measuring elapsed time. This can be accomplished by a standard internal clock of a micro processor that measures time as a series of incremental events at a known rate, such as one event every one hundred milliseconds (0.1 second).
The present invention further comprises the step of selecting one of the first and second groups of data logs. This selection is made as a function of a change in the operating status of the marine propulsion device and as a further function of the identity of a previously selected one of the first and second groups. The change in the operating status of the marine propulsion device is typically a change from an xe2x80x9coffxe2x80x9d condition of the ignition to an xe2x80x9conxe2x80x9d condition of the ignition switch. When this occurs, the present invention determines the current group of data logs that has been most recently used to store data and then switches from that group of data logs to the alternative group of data logs, selected from the first and second groups of data logs. An additional step of the present invention is storing the magnitude of the first parameter as a record in the selected one of the first and second groups of data logs in response to the elapsed time being generally equal to an integral multiple of a preselected time increment. For example, the present invention may be configured to store a new data record in one of the logs when the elapsed time is generally equal to an integral multiple of 0.5 second, 1.0 second, or 5.0 seconds. Other preselected time increments can alternatively be used to determine when data should be stored in the other logs.
In a particularly preferred embodiment of the present invention, each of the first and second groups of data logs comprises three data logs. Each data log comprises 20 records and 7 individual magnitudes of selected parameters are stored in each record. In the particularly preferred embodiment of the present invention, the preselected time increments are 0.5 second, 1.0 second, and 5.0 seconds for the three data logs within each of the first and second groups.
In order to avoid the inadvertent destruction of valuable stored data that is saved prior to an event that needs to be evaluated, a preferred embodiment of the present invention measures the elapsed running time since a most recent change of the operating status (e.g. initiation of ignition) of the marine propulsion system. If the elapsed running time equals or exceeds a predefined magnitude, the data storing step is enabled. Until the elapsed time equals or exceeds a predefined magnitude, the storing step is disabled. In addition, for the purpose of preventing the inadvertent destruction of data following an event that requires analysis, the present invention can also measure an operating characteristic of the marine propulsion device, such as its engine running speed, and then disable the storing step until the operating characteristic equals or exceeds a predefined magnitude. In the case of engine speed, this predefined magnitude can be 400 RPM. In the case when the elapsed running time since the most recent change in the operating status is used to enable or disable the storing step, the predefined magnitude can be 1.0 second.
When the operating status of the marine propulsion device changes, such as when the ignition switch changes from an xe2x80x9coffxe2x80x9d condition to an xe2x80x9conxe2x80x9d condition, the present invention can erase the selected one of the first and second groups of data logs in order to prepare that selected one of the first and second groups for subsequent data storage.
In a data recording method of the present invention, data is continually monitored and stored as long as the engine of the marine propulsion system is operating, with the exception of the initial one second of operation and when the engine is operating at a speed less than 400 RPM. At all other times, data is being stored in the selected one of the first and second groups of data logs. When an event, such as an accident or mechanical failure relating to the marine propulsion device, occurs, causing the engine to cease running, further data storage is inhibited upon a subsequent initiation of ignition. The selected one of the first and second groups then contains sixty records, with twenty records in each log.